Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 241916
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
315 PM EDT Sat Jun 24 2017

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine

.SYNOPSIS...
Issued at 315 PM EDT Sat Jun 24 2017

The area is looking at a an early fall-like pattern with cool
conditions by late June standards along with spotty shower activity.
This pattern will persist at least through Monday before we dry out
some and warm up a little.

Later this week, warmer air will return to the area. With the
arrival of the warmer air, a potentially wet period could take shape
with occasional rounds of showers and storms.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 315 PM EDT Sat Jun 24 2017

The showers and scattered storms mainly over the NE portion of the
area this afternoon should tend to move east of the CWFA within the
next 2-3 hours. Unfortunately, the localized heavier rainfall is
affecting the Mt. Pleasant area which has been hit the hardest over
the last couple of days.

One short wave is about to exit to the east, leaving short wave
ridging to build in briefly. This will be short lived as another
weak wave, and a much stronger wave are moving toward the area from
MN/WI. These will arrive after peak heating, so diurnal instability
will be waning. We do think that the strength of the second wave
will be enough to carry rain chances in later this evening and
overnight.

Another break is order then Sunday morning, before a few
showers/storms will refire Sunday afternoon. This will be the case
as yet another short wave in the cyclonic flow aloft approaches the
area. There does look to be enough instability that thunder will be
possible once again. The westerly flow off of Lake Michigan will
once again shadow the western counties a bit, and allow for the best
rain chances to be over the E and NE.

Cyclonic flow aloft will remain Sunday night into Monday night. This
will mean bouts of showers with isolated thunder, focused on the
peak heating hours. Can not rule out a shower overnight Sunday
night. Monday night, we should tend to end all rain chances and
clear out as the upper low and jet lifts out as we become more anti-
cyclonic aloft.

.LONG TERM...(Tuesday through Saturday)
Issued at 315 PM EDT Sat Jun 24 2017

The big story in the extended is the potential for more heavy rain
during the latter half of the week.

Upper trough axis moves east Tuesday with shortwave ridging
returning Wednesday along with warming temperatures. We will also
see moisture return in southwest flow with chances for rain by
Wednesday afternoon. Surface low center tracks north of Lower
Michigan on Thursday with showers and thunderstorms along and ahead
of trailing cold front slowly pushing south through the forecast
area. The front stalls near southern Lower Michigan and another sfc
low tracks along it on Friday into Saturday with heavy rain and
flooding potential to be watched closely.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 145 PM EDT Sat Jun 24 2017

Mostly VFR conditions through Sunday morning except for some
ceilings in the 1800 to 2500 foot range at times this afternoon
and late Sunday morning. Showers and thunderstorms this afternoon
are expected to stay north of GRR and LAN and east of JXN but
could come close so we will be watching radar trends through 00Z.

Winds will be west 10 to 15 knots and gust over 20 knots at times
this afternoon and again by 18Z Sunday.


&&

.MARINE...
Issued at 315 PM EDT Sat Jun 24 2017

We have expanded the Small Craft Advisory and Beach Hazards
Statement north a couple of marine zones up to Pentwater. We will
see the winds and waves relax for a short time this evening. They
will ramp back up again overnight in association with the passage of
the next wave. The furthest north area will see the gradient a
little bit weaker closer to the core of the low.

It will be possible that additional headlines will be needed on
Monday, or an extension at the very least as the pattern remains
similar through then.

&&

.HYDROLOGY...
Issued at 1231 PM EDT Sat Jun 24 2017

The Chippewa River at Mount Pleasant crested at 14.77 feet Friday
night, about 10 inches below the record flooding of 15.58 feet in
September 1986. All river forecast points in our area have crested
as the water is being routed down through the Muskegon and Saginaw
river systems. Scattered showers Saturday through Monday should
have little effect on the rivers. Heavy rain potential may return
during the latter part of the upcoming week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Sunday evening for MIZ043-050-
     056-064-071.

LM...Small Craft Advisory until 8 PM EDT Sunday for LMZ844>848.

&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...Ostuno
AVIATION...Ostuno
HYDROLOGY...CAS
MARINE...NJJ


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